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<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<title>Document</title>
</head>
<body>
	<script>
		let a1 = 4
		let a2 = 5
		console.log(a1 ,'a1', a2 , 'a2')
		// 变量交换
		let c1
		c1=a1 //4
		a1 = a2 //5
		a2=c1 //4
		console.log(a1 ,'a1', a2 , 'a2')
	</script>
</body>
</html>